The purpose of a tremolo device, of which there are many varieties, is to allow a guitarists to alter an existing string note by an increase or decrease of string tension. Tremolo devices typically include a saddle block and a vice grip, the guitar strings being led over the saddle block and into the vice grip which is then tightened on the saddle block to anchor the strings in position.
A recurring problem with tremolo devices of this construction is string breakage.
While it will never be possible totally to prevent guitar strings breaking for one reason or another, it is far too prevalent with tremolo devices to be acceptable although the professional guitarist tends to put up with the problem because of the advantages, in terms of the variety of sounds and effects, the tremolo device provides.